Stanford researchers to take part in new project to help make sustainable carbon a feedstock material

This article is adapted from a press release from Rice University and one from the Kavli Foundation.

An international team of scientists led by Rice University has won a $4.1 million grant to optimize carbon nanotube synthesis, which could provide more sustainable alternatives to materials now dependent on heavy industry, like steel and other metals, among many other uses. From Korea to England, researchers at 16 universities and other research entities, including Stanford University, are part of the team.

Carbon nanotubes – or “CNTs” – are hollow cylindrical nanoscale structures made from carbon atoms. They are excellent carriers of heat and electricity, are very strong though lightweight, and have a large surface area. They are used today in electronics, biosensors, batteries, and other devices, though on a relatively small scale.

Manufacturing steel, aluminum, and copper generates more than 10 percent of global greenhouse gas emissions. Since net-zero goals require a tripling of the electricity grid, this could result in production of hundreds of millions of tons of these strong and conductive metals. Ultimately, this project seeks to discover if the expansion of the electricity grid – along with massive deployment of green energy technologies – can be accomplished with materials made from CNTs. In theory, CNTs could constitute an ideal net-zero end use for fossil fuels, like natural gas, with the added benefit of clean hydrogen as a reaction byproduct.

However, to efficiently produce high quality CNTs – each about 100,000 times smaller than the width of a human hair – in large, commercial reactors, the physical and chemical processes that drive CNT synthesis must be much better understood. Because CNT synthesis evolved in multiple countries simultaneously, Rice University led the establishment of an international research collaboration to drive that improved understanding.

“Currently, reactors are black boxes, which prevents us from ramping up synthesis efficiency,” said Matteo Pasquali, the project’s leader and professor of chemistry, materials science, and nanoengineering at Rice. “We need to better understand the forces at play in CNT formation by developing new tools to shed light on the reaction zone and find ways to leverage it to our advantage.”

Stanford’s role

The Stanford faculty members involved are Arun Majumdar, dean of the Stanford Doerr School of Sustainability, and Matteo Cargnello, associate professor in the Department of Chemical Engineering.

“We will use catalysts and reactors to decipher how iron surfaces can break down the methane molecule and release hydrogen and grow CNTs. We want to investigate how the iron surface can make different types of carbon,” said Stanford’s Cargnello.

By iron functioning as a catalyst in making CNTs, rather than for making steel, it’s not being melted and consumed. In the CNT process, natural gas is a feedstock, but it is not combusted and the process does not release carbon dioxide.

“The main potential outcome is the opportunity to engineer the process to make hydrogen and CNTs in the cheapest and most efficient way,” Cargnello added.

Stanford researchers have developed methods to accurately measure the type of carbon produced, measure and map the kinetics of individual processes, and measure the rates of formation of CNTs, graphitic carbon, and amorphous carbon.

“I hope the knowledge developed at Stanford will be transferred to other reactor systems that can be used to produce even higher quality CNTs to make fibers and replace other materials, like steel, that are made through hard-to-decarbonize processes,” said Majumdar, who is also a professor of mechanical engineering in the School of Engineering, of energy science and engineering in the Stanford Doerr School of Sustainability, and of photon science at SLAC National Accelerator Laboratory.

“Rice has put together a great team of experts across several disciplines to collaborate on a new and important project, and the external funding has validated this pursuit’s potential benefits as part of a more sustainable future,” Majumdar added.

Fun fact

The conception and first demonstration of synthesis of CNTs from methane was a Rice-Stanford collaboration in the late 1990s.

“The breakthrough involved Rice's Rick Smalley, who won the chemistry Nobel in 1996, and his postdoc Hongjie Dai, who demonstrated the process shortly after joining the Stanford faculty,” said Pasquali. “Now Rice and Stanford get to work together again at better understanding the process and making it efficient!”

Other universities and research institutions involved are: University of Cambridge, Politecnico di Milano, UC-Santa Barbara, MIT, University of Minnesota, Harvard, University of Pennsylvania, Pennsylvania State University, the National Renewable Energy Laboratory the National Institute of Standards & Technology, the Korea Institute of Science & Technology, the Air Force Research Laboratory, Argonne National Laboratory, and the Madrid Institute for Advanced Studies.

This project is funded by the Kavli Foundation Exploration Award in Nanoscience for Sustainability and Rice’s Carbon Hub, which Pasquali directs.